This invention relates to a process for deposition of films of boron nitrides or other binary boron films, such as boron phosphide, boron carbide, boron silicide, boron arsenide, etc. as well as to the deposition and subsequent doping of boron. The invention is more particularly directed to deposition, such as by plasma assisted deposition of BN films or the like from a mixture of decaborane and another gas such as nitrogen, ammonia, methane, silane, etc. to combine with boron in the film. Boron nitride is useful in many applications, and particularly in semiconductor electronics, because of its high resistivity, insulating, and dielectric properties. Desirably, boron nitride should be deposited in cubic form which is similar to the diamond lattice structure of silicon, gallium arsenide, or zinc sulfide. Boron nitride coatings are also useful as corrosion resistant, anti-reflective hard durable coatings in a number of applications.
Boron carbide, boron phosphide, boron arsenide, and other binary layers based on boron and another element each have particular utilities which are well known and documented.
Several previous processes for depositing boron nitride films are described, for example, in U.S. Pat. Nos. 4,714,625; 4,656,052; 4,622,236; 4,412,899; 4,415,420; 4,297,387; 3,692,566; 3,499,799; and 3,152,066.
In U.S. Pat. No. 4,522,849 is disclosed a process for coating a quartz substrate with boron nitride. In that process ammonia and diborane gases are mixed and flowed past the quartz substrate, which has been heated to about 1000.degree. C. The diborane and ammonia gases react to produce the boron nitride film. Other processes employ other starting vapors; U.S. Pat. No. 4,714,625 describes mixing of boric acid and ammonia to form a boron nitride layer.
None of these previous techniques is adaptable to depositing boron nitride and boron in patterns. However, it would be highly desirable to do this so that the technique can be used in very large scale circuit integration (VLSI) as a single-step deposition process in forming insulation, barriers, or resistors. Such a technique would make more reliable, more highly integrated electronic devices at a lower cost.